_ Git - rust-lightning/blob - lightning/src/routing/scoring.rs

   1 // This file is Copyright its original authors, visible in version control
   2 // history.
   3 //
   4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
   5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
   7 // You may not use this file except in accordance with one or both of these
   8 // licenses.
   9
  10 //! Utilities for scoring payment channels.
  11 //!
  12 //! [`Scorer`] may be given to [`find_route`] to score payment channels during path finding when a
  13 //! custom [`Score`] implementation is not needed.
  14 //!
  15 //! # Example
  16 //!
  17 //! ```
  18 //! # extern crate secp256k1;
  19 //! #
  20 //! # use lightning::routing::network_graph::NetworkGraph;
  21 //! # use lightning::routing::router::{RouteParameters, find_route};
  22 //! # use lightning::routing::scoring::{Scorer, ScoringParameters};
  23 //! # use lightning::util::logger::{Logger, Record};
  24 //! # use secp256k1::key::PublicKey;
  25 //! #
  26 //! # struct FakeLogger {};
  27 //! # impl Logger for FakeLogger {
  28 //! #     fn log(&self, record: &Record) { unimplemented!() }
  29 //! # }
  30 //! # fn find_scored_route(payer: PublicKey, params: RouteParameters, network_graph: NetworkGraph) {
  31 //! # let logger = FakeLogger {};
  32 //! #
  33 //! // Use the default channel penalties.
  34 //! let scorer = Scorer::default();
  35 //!
  36 //! // Or use custom channel penalties.
  37 //! let scorer = Scorer::new(ScoringParameters {
  38 //!     base_penalty_msat: 1000,
  39 //!     failure_penalty_msat: 2 * 1024 * 1000,
  40 //!     ..ScoringParameters::default()
  41 //! });
  42 //!
  43 //! let route = find_route(&payer, &params, &network_graph, None, &logger, &scorer);
  44 //! # }
  45 //! ```
  46 //!
  47 //! # Note
  48 //!
  49 //! Persisting when built with feature `no-std` and restoring without it, or vice versa, uses
  50 //! different types and thus is undefined.
  51 //!
  52 //! [`find_route`]: crate::routing::router::find_route
  53
  54 use ln::msgs::DecodeError;
  55 use routing::network_graph::NodeId;
  56 use routing::router::RouteHop;
  57 use util::ser::{Readable, Writeable, Writer};
  58
  59 use prelude::*;
  60 use core::cell::{RefCell, RefMut};
  61 use core::ops::DerefMut;
  62 use core::time::Duration;
  63 use io::{self, Read};
  64 use sync::{Mutex, MutexGuard};
  65
  66 /// We define Score ever-so-slightly differently based on whether we are being built for C bindings
  67 /// or not. For users, `LockableScore` must somehow be writeable to disk. For Rust users, this is
  68 /// no problem - you move a `Score` that implements `Writeable` into a `Mutex`, lock it, and now
  69 /// you have the original, concrete, `Score` type, which presumably implements `Writeable`.
  70 ///
  71 /// For C users, once you've moved the `Score` into a `LockableScore` all you have after locking it
  72 /// is an opaque trait object with an opaque pointer with no type info. Users could take the unsafe
  73 /// approach of blindly casting that opaque pointer to a concrete type and calling `Writeable` from
  74 /// there, but other languages downstream of the C bindings (e.g. Java) can't even do that.
  75 /// Instead, we really want `Score` and `LockableScore` to implement `Writeable` directly, which we
  76 /// do here by defining `Score` differently for `cfg(c_bindings)`.
  77 macro_rules! define_score { ($($supertrait: path)*) => {
  78 /// An interface used to score payment channels for path finding.
  79 ///
  80 ///     Scoring is in terms of fees willing to be paid in order to avoid routing through a channel.
  81 pub trait Score $(: $supertrait)* {
  82         /// Returns the fee in msats willing to be paid to avoid routing `send_amt_msat` through the
  83         /// given channel in the direction from `source` to `target`.
  84         ///
  85         /// The channel's capacity (less any other MPP parts which are also being considered for use in
  86         /// the same payment) is given by `channel_capacity_msat`. It may be guessed from various
  87         /// sources or assumed from no data at all.
  88         ///
  89         /// For hints provided in the invoice, we assume the channel has sufficient capacity to accept
  90         /// the invoice's full amount, and provide a `channel_capacity_msat` of `None`. In all other
  91         /// cases it is set to `Some`, even if we're guessing at the channel value.
  92         ///
  93         /// Your code should be overflow-safe through a `channel_capacity_msat` of 21 million BTC.
  94         fn channel_penalty_msat(&self, short_channel_id: u64, send_amt_msat: u64, channel_capacity_msat: Option<u64>, source: &NodeId, target: &NodeId) -> u64;
  95
  96         /// Handles updating channel penalties after failing to route through a channel.
  97         fn payment_path_failed(&mut self, path: &[&RouteHop], short_channel_id: u64);
  98
  99         /// Handles updating channel penalties after successfully routing along a path.
 100         fn payment_path_successful(&mut self, path: &[&RouteHop]);
 101 }
 102
 103 impl<S: Score, T: DerefMut<Target=S> $(+ $supertrait)*> Score for T {
 104         fn channel_penalty_msat(&self, short_channel_id: u64, send_amt_msat: u64, channel_capacity_msat: Option<u64>, source: &NodeId, target: &NodeId) -> u64 {
 105                 self.deref().channel_penalty_msat(short_channel_id, send_amt_msat, channel_capacity_msat, source, target)
 106         }
 107
 108         fn payment_path_failed(&mut self, path: &[&RouteHop], short_channel_id: u64) {
 109                 self.deref_mut().payment_path_failed(path, short_channel_id)
 110         }
 111
 112         fn payment_path_successful(&mut self, path: &[&RouteHop]) {
 113                 self.deref_mut().payment_path_successful(path)
 114         }
 115 }
 116 } }
 117
 118 #[cfg(c_bindings)]
 119 define_score!(Writeable);
 120 #[cfg(not(c_bindings))]
 121 define_score!();
 122
 123 /// A scorer that is accessed under a lock.
 124 ///
 125 /// Needed so that calls to [`Score::channel_penalty_msat`] in [`find_route`] can be made while
 126 /// having shared ownership of a scorer but without requiring internal locking in [`Score`]
 127 /// implementations. Internal locking would be detrimental to route finding performance and could
 128 /// result in [`Score::channel_penalty_msat`] returning a different value for the same channel.
 129 ///
 130 /// [`find_route`]: crate::routing::router::find_route
 131 pub trait LockableScore<'a> {
 132         /// The locked [`Score`] type.
 133         type Locked: 'a + Score;
 134
 135         /// Returns the locked scorer.
 136         fn lock(&'a self) -> Self::Locked;
 137 }
 138
 139 /// (C-not exported)
 140 impl<'a, T: 'a + Score> LockableScore<'a> for Mutex<T> {
 141         type Locked = MutexGuard<'a, T>;
 142
 143         fn lock(&'a self) -> MutexGuard<'a, T> {
 144                 Mutex::lock(self).unwrap()
 145         }
 146 }
 147
 148 impl<'a, T: 'a + Score> LockableScore<'a> for RefCell<T> {
 149         type Locked = RefMut<'a, T>;
 150
 151         fn lock(&'a self) -> RefMut<'a, T> {
 152                 self.borrow_mut()
 153         }
 154 }
 155
 156 #[cfg(c_bindings)]
 157 /// A concrete implementation of [`LockableScore`] which supports multi-threading.
 158 pub struct MultiThreadedLockableScore<S: Score> {
 159         score: Mutex<S>,
 160 }
 161 #[cfg(c_bindings)]
 162 /// (C-not exported)
 163 impl<'a, T: Score + 'a> LockableScore<'a> for MultiThreadedLockableScore<T> {
 164         type Locked = MutexGuard<'a, T>;
 165
 166         fn lock(&'a self) -> MutexGuard<'a, T> {
 167                 Mutex::lock(&self.score).unwrap()
 168         }
 169 }
 170
 171 #[cfg(c_bindings)]
 172 /// (C-not exported)
 173 impl<'a, T: Writeable> Writeable for RefMut<'a, T> {
 174         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 175                 T::write(&**self, writer)
 176         }
 177 }
 178
 179 #[cfg(c_bindings)]
 180 /// (C-not exported)
 181 impl<'a, S: Writeable> Writeable for MutexGuard<'a, S> {
 182         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 183                 S::write(&**self, writer)
 184         }
 185 }
 186
 187 /// [`Score`] implementation that provides reasonable default behavior.
 188 ///
 189 /// Used to apply a fixed penalty to each channel, thus avoiding long paths when shorter paths with
 190 /// slightly higher fees are available. Will further penalize channels that fail to relay payments.
 191 ///
 192 /// See [module-level documentation] for usage.
 193 ///
 194 /// [module-level documentation]: crate::routing::scoring
 195 #[cfg(not(feature = "no-std"))]
 196 pub type Scorer = ScorerUsingTime::<std::time::Instant>;
 197 /// [`Score`] implementation that provides reasonable default behavior.
 198 ///
 199 /// Used to apply a fixed penalty to each channel, thus avoiding long paths when shorter paths with
 200 /// slightly higher fees are available. Will further penalize channels that fail to relay payments.
 201 ///
 202 /// See [module-level documentation] for usage and [`ScoringParameters`] for customization.
 203 ///
 204 /// [module-level documentation]: crate::routing::scoring
 205 #[cfg(feature = "no-std")]
 206 pub type Scorer = ScorerUsingTime::<time::Eternity>;
 207
 208 // Note that ideally we'd hide ScorerUsingTime from public view by sealing it as well, but rustdoc
 209 // doesn't handle this well - instead exposing a `Scorer` which has no trait implementation(s) or
 210 // methods at all.
 211
 212 /// [`Score`] implementation.
 213 ///
 214 /// See [`Scorer`] for details.
 215 ///
 216 /// # Note
 217 ///
 218 /// Mixing the `no-std` feature between serialization and deserialization results in undefined
 219 /// behavior.
 220 ///
 221 /// (C-not exported) generally all users should use the [`Scorer`] type alias.
 222 pub struct ScorerUsingTime<T: Time> {
 223         params: ScoringParameters,
 224         // TODO: Remove entries of closed channels.
 225         channel_failures: HashMap<u64, ChannelFailure<T>>,
 226 }
 227
 228 /// Parameters for configuring [`Scorer`].
 229 pub struct ScoringParameters {
 230         /// A fixed penalty in msats to apply to each channel.
 231         ///
 232         /// Default value: 500 msat
 233         pub base_penalty_msat: u64,
 234
 235         /// A penalty in msats to apply to a channel upon failing to relay a payment.
 236         ///
 237         /// This accumulates for each failure but may be reduced over time based on
 238         /// [`failure_penalty_half_life`] or when successfully routing through a channel.
 239         ///
 240         /// Default value: 1,024,000 msat
 241         ///
 242         /// [`failure_penalty_half_life`]: Self::failure_penalty_half_life
 243         pub failure_penalty_msat: u64,
 244
 245         /// When the amount being sent over a channel is this many 1024ths of the total channel
 246         /// capacity, we begin applying [`overuse_penalty_msat_per_1024th`].
 247         ///
 248         /// Default value: 128 1024ths (i.e. begin penalizing when an HTLC uses 1/8th of a channel)
 249         ///
 250         /// [`overuse_penalty_msat_per_1024th`]: Self::overuse_penalty_msat_per_1024th
 251         pub overuse_penalty_start_1024th: u16,
 252
 253         /// A penalty applied, per whole 1024ths of the channel capacity which the amount being sent
 254         /// over the channel exceeds [`overuse_penalty_start_1024th`] by.
 255         ///
 256         /// Default value: 20 msat (i.e. 2560 msat penalty to use 1/4th of a channel, 7680 msat penalty
 257         ///                to use half a channel, and 12,560 msat penalty to use 3/4ths of a channel)
 258         ///
 259         /// [`overuse_penalty_start_1024th`]: Self::overuse_penalty_start_1024th
 260         pub overuse_penalty_msat_per_1024th: u64,
 261
 262         /// The time required to elapse before any accumulated [`failure_penalty_msat`] penalties are
 263         /// cut in half.
 264         ///
 265         /// Successfully routing through a channel will immediately cut the penalty in half as well.
 266         ///
 267         /// # Note
 268         ///
 269         /// When built with the `no-std` feature, time will never elapse. Therefore, this penalty will
 270         /// never decay.
 271         ///
 272         /// [`failure_penalty_msat`]: Self::failure_penalty_msat
 273         pub failure_penalty_half_life: Duration,
 274 }
 275
 276 impl_writeable_tlv_based!(ScoringParameters, {
 277         (0, base_penalty_msat, required),
 278         (1, overuse_penalty_start_1024th, (default_value, 128)),
 279         (2, failure_penalty_msat, required),
 280         (3, overuse_penalty_msat_per_1024th, (default_value, 20)),
 281         (4, failure_penalty_half_life, required),
 282 });
 283
 284 /// Accounting for penalties against a channel for failing to relay any payments.
 285 ///
 286 /// Penalties decay over time, though accumulate as more failures occur.
 287 struct ChannelFailure<T: Time> {
 288         /// Accumulated penalty in msats for the channel as of `last_updated`.
 289         undecayed_penalty_msat: u64,
 290
 291         /// Last time the channel either failed to route or successfully routed a payment. Used to decay
 292         /// `undecayed_penalty_msat`.
 293         last_updated: T,
 294 }
 295
 296 impl<T: Time> ScorerUsingTime<T> {
 297         /// Creates a new scorer using the given scoring parameters.
 298         pub fn new(params: ScoringParameters) -> Self {
 299                 Self {
 300                         params,
 301                         channel_failures: HashMap::new(),
 302                 }
 303         }
 304
 305         /// Creates a new scorer using `penalty_msat` as a fixed channel penalty.
 306         #[cfg(any(test, feature = "fuzztarget", feature = "_test_utils"))]
 307         pub fn with_fixed_penalty(penalty_msat: u64) -> Self {
 308                 Self::new(ScoringParameters {
 309                         base_penalty_msat: penalty_msat,
 310                         failure_penalty_msat: 0,
 311                         failure_penalty_half_life: Duration::from_secs(0),
 312                         overuse_penalty_start_1024th: 1024,
 313                         overuse_penalty_msat_per_1024th: 0,
 314                 })
 315         }
 316 }
 317
 318 impl<T: Time> ChannelFailure<T> {
 319         fn new(failure_penalty_msat: u64) -> Self {
 320                 Self {
 321                         undecayed_penalty_msat: failure_penalty_msat,
 322                         last_updated: T::now(),
 323                 }
 324         }
 325
 326         fn add_penalty(&mut self, failure_penalty_msat: u64, half_life: Duration) {
 327                 self.undecayed_penalty_msat = self.decayed_penalty_msat(half_life) + failure_penalty_msat;
 328                 self.last_updated = T::now();
 329         }
 330
 331         fn reduce_penalty(&mut self, half_life: Duration) {
 332                 self.undecayed_penalty_msat = self.decayed_penalty_msat(half_life) >> 1;
 333                 self.last_updated = T::now();
 334         }
 335
 336         fn decayed_penalty_msat(&self, half_life: Duration) -> u64 {
 337                 let decays = self.last_updated.elapsed().as_secs().checked_div(half_life.as_secs());
 338                 match decays {
 339                         Some(decays) => self.undecayed_penalty_msat >> decays,
 340                         None => 0,
 341                 }
 342         }
 343 }
 344
 345 impl<T: Time> Default for ScorerUsingTime<T> {
 346         fn default() -> Self {
 347                 Self::new(ScoringParameters::default())
 348         }
 349 }
 350
 351 impl Default for ScoringParameters {
 352         fn default() -> Self {
 353                 Self {
 354                         base_penalty_msat: 500,
 355                         failure_penalty_msat: 1024 * 1000,
 356                         failure_penalty_half_life: Duration::from_secs(3600),
 357                         overuse_penalty_start_1024th: 1024 / 8,
 358                         overuse_penalty_msat_per_1024th: 20,
 359                 }
 360         }
 361 }
 362
 363 impl<T: Time> Score for ScorerUsingTime<T> {
 364         fn channel_penalty_msat(
 365                 &self, short_channel_id: u64, send_amt_msat: u64, chan_capacity_opt: Option<u64>, _source: &NodeId, _target: &NodeId
 366         ) -> u64 {
 367                 let failure_penalty_msat = self.channel_failures
 368                         .get(&short_channel_id)
 369                         .map_or(0, |value| value.decayed_penalty_msat(self.params.failure_penalty_half_life));
 370
 371                 let mut penalty_msat = self.params.base_penalty_msat + failure_penalty_msat;
 372
 373                 if let Some(chan_capacity_msat) = chan_capacity_opt {
 374                         let send_1024ths = send_amt_msat.checked_mul(1024).unwrap_or(u64::max_value()) / chan_capacity_msat;
 375
 376                         if send_1024ths > self.params.overuse_penalty_start_1024th as u64 {
 377                                 penalty_msat = penalty_msat.checked_add(
 378                                                 (send_1024ths - self.params.overuse_penalty_start_1024th as u64)
 379                                                 .checked_mul(self.params.overuse_penalty_msat_per_1024th).unwrap_or(u64::max_value()))
 380                                         .unwrap_or(u64::max_value());
 381                         }
 382                 }
 383
 384                 penalty_msat
 385         }
 386
 387         fn payment_path_failed(&mut self, _path: &[&RouteHop], short_channel_id: u64) {
 388                 let failure_penalty_msat = self.params.failure_penalty_msat;
 389                 let half_life = self.params.failure_penalty_half_life;
 390                 self.channel_failures
 391                         .entry(short_channel_id)
 392                         .and_modify(|failure| failure.add_penalty(failure_penalty_msat, half_life))
 393                         .or_insert_with(|| ChannelFailure::new(failure_penalty_msat));
 394         }
 395
 396         fn payment_path_successful(&mut self, path: &[&RouteHop]) {
 397                 let half_life = self.params.failure_penalty_half_life;
 398                 for hop in path.iter() {
 399                         self.channel_failures
 400                                 .entry(hop.short_channel_id)
 401                                 .and_modify(|failure| failure.reduce_penalty(half_life));
 402                 }
 403         }
 404 }
 405
 406 impl<T: Time> Writeable for ScorerUsingTime<T> {
 407         #[inline]
 408         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 409                 self.params.write(w)?;
 410                 self.channel_failures.write(w)?;
 411                 write_tlv_fields!(w, {});
 412                 Ok(())
 413         }
 414 }
 415
 416 impl<T: Time> Readable for ScorerUsingTime<T> {
 417         #[inline]
 418         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 419                 let res = Ok(Self {
 420                         params: Readable::read(r)?,
 421                         channel_failures: Readable::read(r)?,
 422                 });
 423                 read_tlv_fields!(r, {});
 424                 res
 425         }
 426 }
 427
 428 impl<T: Time> Writeable for ChannelFailure<T> {
 429         #[inline]
 430         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 431                 let duration_since_epoch = T::duration_since_epoch() - self.last_updated.elapsed();
 432                 write_tlv_fields!(w, {
 433                         (0, self.undecayed_penalty_msat, required),
 434                         (2, duration_since_epoch, required),
 435                 });
 436                 Ok(())
 437         }
 438 }
 439
 440 impl<T: Time> Readable for ChannelFailure<T> {
 441         #[inline]
 442         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 443                 let mut undecayed_penalty_msat = 0;
 444                 let mut duration_since_epoch = Duration::from_secs(0);
 445                 read_tlv_fields!(r, {
 446                         (0, undecayed_penalty_msat, required),
 447                         (2, duration_since_epoch, required),
 448                 });
 449                 Ok(Self {
 450                         undecayed_penalty_msat,
 451                         last_updated: T::now() - (T::duration_since_epoch() - duration_since_epoch),
 452                 })
 453         }
 454 }
 455
 456 pub(crate) mod time {
 457         use core::ops::Sub;
 458         use core::time::Duration;
 459         /// A measurement of time.
 460         pub trait Time: Sub<Duration, Output = Self> where Self: Sized {
 461                 /// Returns an instance corresponding to the current moment.
 462                 fn now() -> Self;
 463
 464                 /// Returns the amount of time elapsed since `self` was created.
 465                 fn elapsed(&self) -> Duration;
 466
 467                 /// Returns the amount of time passed since the beginning of [`Time`].
 468                 ///
 469                 /// Used during (de-)serialization.
 470                 fn duration_since_epoch() -> Duration;
 471         }
 472
 473         /// A state in which time has no meaning.
 474         #[derive(Debug, PartialEq, Eq)]
 475         pub struct Eternity;
 476
 477         #[cfg(not(feature = "no-std"))]
 478         impl Time for std::time::Instant {
 479                 fn now() -> Self {
 480                         std::time::Instant::now()
 481                 }
 482
 483                 fn duration_since_epoch() -> Duration {
 484                         use std::time::SystemTime;
 485                         SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap()
 486                 }
 487
 488                 fn elapsed(&self) -> Duration {
 489                         std::time::Instant::elapsed(self)
 490                 }
 491         }
 492
 493         impl Time for Eternity {
 494                 fn now() -> Self {
 495                         Self
 496                 }
 497
 498                 fn duration_since_epoch() -> Duration {
 499                         Duration::from_secs(0)
 500                 }
 501
 502                 fn elapsed(&self) -> Duration {
 503                         Duration::from_secs(0)
 504                 }
 505         }
 506
 507         impl Sub<Duration> for Eternity {
 508                 type Output = Self;
 509
 510                 fn sub(self, _other: Duration) -> Self {
 511                         self
 512                 }
 513         }
 514 }
 515
 516 pub(crate) use self::time::Time;
 517
 518 #[cfg(test)]
 519 mod tests {
 520         use super::{ScoringParameters, ScorerUsingTime, Time};
 521         use super::time::Eternity;
 522
 523         use ln::features::{ChannelFeatures, NodeFeatures};
 524         use routing::scoring::Score;
 525         use routing::network_graph::NodeId;
 526         use routing::router::RouteHop;
 527         use util::ser::{Readable, Writeable};
 528
 529         use bitcoin::secp256k1::PublicKey;
 530         use core::cell::Cell;
 531         use core::ops::Sub;
 532         use core::time::Duration;
 533         use io;
 534
 535         /// Time that can be advanced manually in tests.
 536         #[derive(Debug, PartialEq, Eq)]
 537         struct SinceEpoch(Duration);
 538
 539         impl SinceEpoch {
 540                 thread_local! {
 541                         static ELAPSED: Cell<Duration> = core::cell::Cell::new(Duration::from_secs(0));
 542                 }
 543
 544                 fn advance(duration: Duration) {
 545                         Self::ELAPSED.with(|elapsed| elapsed.set(elapsed.get() + duration))
 546                 }
 547         }
 548
 549         impl Time for SinceEpoch {
 550                 fn now() -> Self {
 551                         Self(Self::duration_since_epoch())
 552                 }
 553
 554                 fn duration_since_epoch() -> Duration {
 555                         Self::ELAPSED.with(|elapsed| elapsed.get())
 556                 }
 557
 558                 fn elapsed(&self) -> Duration {
 559                         Self::duration_since_epoch() - self.0
 560                 }
 561         }
 562
 563         impl Sub<Duration> for SinceEpoch {
 564                 type Output = Self;
 565
 566                 fn sub(self, other: Duration) -> Self {
 567                         Self(self.0 - other)
 568                 }
 569         }
 570
 571         #[test]
 572         fn time_passes_when_advanced() {
 573                 let now = SinceEpoch::now();
 574                 assert_eq!(now.elapsed(), Duration::from_secs(0));
 575
 576                 SinceEpoch::advance(Duration::from_secs(1));
 577                 SinceEpoch::advance(Duration::from_secs(1));
 578
 579                 let elapsed = now.elapsed();
 580                 let later = SinceEpoch::now();
 581
 582                 assert_eq!(elapsed, Duration::from_secs(2));
 583                 assert_eq!(later - elapsed, now);
 584         }
 585
 586         #[test]
 587         fn time_never_passes_in_an_eternity() {
 588                 let now = Eternity::now();
 589                 let elapsed = now.elapsed();
 590                 let later = Eternity::now();
 591
 592                 assert_eq!(now.elapsed(), Duration::from_secs(0));
 593                 assert_eq!(later - elapsed, now);
 594         }
 595
 596         /// A scorer for testing with time that can be manually advanced.
 597         type Scorer = ScorerUsingTime::<SinceEpoch>;
 598
 599         fn source_node_id() -> NodeId {
 600                 NodeId::from_pubkey(&PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap())
 601         }
 602
 603         fn target_node_id() -> NodeId {
 604                 NodeId::from_pubkey(&PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap())
 605         }
 606
 607         #[test]
 608         fn penalizes_without_channel_failures() {
 609                 let scorer = Scorer::new(ScoringParameters {
 610                         base_penalty_msat: 1_000,
 611                         failure_penalty_msat: 512,
 612                         failure_penalty_half_life: Duration::from_secs(1),
 613                         overuse_penalty_start_1024th: 1024,
 614                         overuse_penalty_msat_per_1024th: 0,
 615                 });
 616                 let source = source_node_id();
 617                 let target = target_node_id();
 618                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 619
 620                 SinceEpoch::advance(Duration::from_secs(1));
 621                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 622         }
 623
 624         #[test]
 625         fn accumulates_channel_failure_penalties() {
 626                 let mut scorer = Scorer::new(ScoringParameters {
 627                         base_penalty_msat: 1_000,
 628                         failure_penalty_msat: 64,
 629                         failure_penalty_half_life: Duration::from_secs(10),
 630                         overuse_penalty_start_1024th: 1024,
 631                         overuse_penalty_msat_per_1024th: 0,
 632                 });
 633                 let source = source_node_id();
 634                 let target = target_node_id();
 635                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 636
 637                 scorer.payment_path_failed(&[], 42);
 638                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_064);
 639
 640                 scorer.payment_path_failed(&[], 42);
 641                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_128);
 642
 643                 scorer.payment_path_failed(&[], 42);
 644                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_192);
 645         }
 646
 647         #[test]
 648         fn decays_channel_failure_penalties_over_time() {
 649                 let mut scorer = Scorer::new(ScoringParameters {
 650                         base_penalty_msat: 1_000,
 651                         failure_penalty_msat: 512,
 652                         failure_penalty_half_life: Duration::from_secs(10),
 653                         overuse_penalty_start_1024th: 1024,
 654                         overuse_penalty_msat_per_1024th: 0,
 655                 });
 656                 let source = source_node_id();
 657                 let target = target_node_id();
 658                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 659
 660                 scorer.payment_path_failed(&[], 42);
 661                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 662
 663                 SinceEpoch::advance(Duration::from_secs(9));
 664                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 665
 666                 SinceEpoch::advance(Duration::from_secs(1));
 667                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 668
 669                 SinceEpoch::advance(Duration::from_secs(10 * 8));
 670                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_001);
 671
 672                 SinceEpoch::advance(Duration::from_secs(10));
 673                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 674
 675                 SinceEpoch::advance(Duration::from_secs(10));
 676                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 677         }
 678
 679         #[test]
 680         fn accumulates_channel_failure_penalties_after_decay() {
 681                 let mut scorer = Scorer::new(ScoringParameters {
 682                         base_penalty_msat: 1_000,
 683                         failure_penalty_msat: 512,
 684                         failure_penalty_half_life: Duration::from_secs(10),
 685                         overuse_penalty_start_1024th: 1024,
 686                         overuse_penalty_msat_per_1024th: 0,
 687                 });
 688                 let source = source_node_id();
 689                 let target = target_node_id();
 690                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 691
 692                 scorer.payment_path_failed(&[], 42);
 693                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 694
 695                 SinceEpoch::advance(Duration::from_secs(10));
 696                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 697
 698                 scorer.payment_path_failed(&[], 42);
 699                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_768);
 700
 701                 SinceEpoch::advance(Duration::from_secs(10));
 702                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_384);
 703         }
 704
 705         #[test]
 706         fn reduces_channel_failure_penalties_after_success() {
 707                 let mut scorer = Scorer::new(ScoringParameters {
 708                         base_penalty_msat: 1_000,
 709                         failure_penalty_msat: 512,
 710                         failure_penalty_half_life: Duration::from_secs(10),
 711                         overuse_penalty_start_1024th: 1024,
 712                         overuse_penalty_msat_per_1024th: 0,
 713                 });
 714                 let source = source_node_id();
 715                 let target = target_node_id();
 716                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 717
 718                 scorer.payment_path_failed(&[], 42);
 719                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 720
 721                 SinceEpoch::advance(Duration::from_secs(10));
 722                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 723
 724                 let hop = RouteHop {
 725                         pubkey: PublicKey::from_slice(target.as_slice()).unwrap(),
 726                         node_features: NodeFeatures::known(),
 727                         short_channel_id: 42,
 728                         channel_features: ChannelFeatures::known(),
 729                         fee_msat: 1,
 730                         cltv_expiry_delta: 18,
 731                 };
 732                 scorer.payment_path_successful(&[&hop]);
 733                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_128);
 734
 735                 SinceEpoch::advance(Duration::from_secs(10));
 736                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_064);
 737         }
 738
 739         #[test]
 740         fn restores_persisted_channel_failure_penalties() {
 741                 let mut scorer = Scorer::new(ScoringParameters {
 742                         base_penalty_msat: 1_000,
 743                         failure_penalty_msat: 512,
 744                         failure_penalty_half_life: Duration::from_secs(10),
 745                         overuse_penalty_start_1024th: 1024,
 746                         overuse_penalty_msat_per_1024th: 0,
 747                 });
 748                 let source = source_node_id();
 749                 let target = target_node_id();
 750
 751                 scorer.payment_path_failed(&[], 42);
 752                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 753
 754                 SinceEpoch::advance(Duration::from_secs(10));
 755                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 756
 757                 scorer.payment_path_failed(&[], 43);
 758                 assert_eq!(scorer.channel_penalty_msat(43, 1, Some(1), &source, &target), 1_512);
 759
 760                 let mut serialized_scorer = Vec::new();
 761                 scorer.write(&mut serialized_scorer).unwrap();
 762
 763                 let deserialized_scorer = <Scorer>::read(&mut io::Cursor::new(&serialized_scorer)).unwrap();
 764                 assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 765                 assert_eq!(deserialized_scorer.channel_penalty_msat(43, 1, Some(1), &source, &target), 1_512);
 766         }
 767
 768         #[test]
 769         fn decays_persisted_channel_failure_penalties() {
 770                 let mut scorer = Scorer::new(ScoringParameters {
 771                         base_penalty_msat: 1_000,
 772                         failure_penalty_msat: 512,
 773                         failure_penalty_half_life: Duration::from_secs(10),
 774                         overuse_penalty_start_1024th: 1024,
 775                         overuse_penalty_msat_per_1024th: 0,
 776                 });
 777                 let source = source_node_id();
 778                 let target = target_node_id();
 779
 780                 scorer.payment_path_failed(&[], 42);
 781                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 782
 783                 let mut serialized_scorer = Vec::new();
 784                 scorer.write(&mut serialized_scorer).unwrap();
 785
 786                 SinceEpoch::advance(Duration::from_secs(10));
 787
 788                 let deserialized_scorer = <Scorer>::read(&mut io::Cursor::new(&serialized_scorer)).unwrap();
 789                 assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 790
 791                 SinceEpoch::advance(Duration::from_secs(10));
 792                 assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_128);
 793         }
 794
 795         #[test]
 796         fn charges_per_1024th_penalty() {
 797                 let scorer = Scorer::new(ScoringParameters {
 798                         base_penalty_msat: 0,
 799                         failure_penalty_msat: 0,
 800                         failure_penalty_half_life: Duration::from_secs(0),
 801                         overuse_penalty_start_1024th: 256,
 802                         overuse_penalty_msat_per_1024th: 100,
 803                 });
 804                 let source = source_node_id();
 805                 let target = target_node_id();
 806
 807                 assert_eq!(scorer.channel_penalty_msat(42, 1_000, None, &source, &target), 0);
 808                 assert_eq!(scorer.channel_penalty_msat(42, 1_000, Some(1_024_000), &source, &target), 0);
 809                 assert_eq!(scorer.channel_penalty_msat(42, 256_999, Some(1_024_000), &source, &target), 0);
 810                 assert_eq!(scorer.channel_penalty_msat(42, 257_000, Some(1_024_000), &source, &target), 100);
 811                 assert_eq!(scorer.channel_penalty_msat(42, 258_000, Some(1_024_000), &source, &target), 200);
 812                 assert_eq!(scorer.channel_penalty_msat(42, 512_000, Some(1_024_000), &source, &target), 256 * 100);
 813         }
 814 }